If Data was a woman the writers would have never explored what it meant to be human, which was the purpose of the character to begin with. They would have just turned her into somebody's girlfriend, like they did with Troi and Crusher. It would have been the easy way out.
I assume you've never seen most eps of TNG featuring them? That, or I'm misunderstanding your post. Troi's relationship with Riker was an ongoing character arc, and Crusher getting with Picard is only visited a few times in all of TNG.
And if you mean the romance-of-the-week junk, then EVERY character had that rubbish.